TY - GEN AU - Schaefer, Johannes Sebastian ID - 689 TI - Routing Algorithms on Delayed Networks for Disaster Management Support ER - TY - GEN AB - In this paper, we solve the local gathering problem of a swarm of $n$ indistinguishable, point-shaped robots on a two dimensional grid in asymptotically optimal time $\mathcal{O}(n)$ in the fully synchronous $\mathcal{FSYNC}$ time model. Given an arbitrarily distributed (yet connected) swarm of robots, the gathering problem on the grid is to locate all robots within a $2\times 2$-sized area that is not known beforehand. Two robots are connected if they are vertical or horizontal neighbors on the grid. The locality constraint means that no global control, no compass, no global communication and only local vision is available; hence, a robot can only see its grid neighbors up to a constant $L_1$-distance, which also limits its movements. A robot can move to one of its eight neighboring grid cells and if two or more robots move to the same location they are \emph{merged} to be only one robot. The locality constraint is the significant challenging issue here, since robot movements must not harm the (only globally checkable) swarm connectivity. For solving the gathering problem, we provide a synchronous algorithm -- executed by every robot -- which ensures that robots merge without breaking the swarm connectivity. In our model, robots can obtain a special state, which marks such a robot to be performing specific connectivity preserving movements in order to allow later merge operations of the swarm. Compared to the grid, for gathering in the Euclidean plane for the same robot and time model the best known upper bound is $\mathcal{O}(n^2)$. AU - Cord-Landwehr, Andreas AU - Fischer, Matthias AU - Jung, Daniel AU - Meyer auf der Heide, Friedhelm ID - 16450 T2 - arXiv:1602.03303 TI - Asymptotically Optimal Gathering on a Grid ER - TY - CONF AB - We apply methods of genetic programming to a general problem from software engineering, namely example-based generation of specifications. In particular, we focus on model transformation by example. The definition and implementation of model transformations is a task frequently carried out by domain experts, hence, a (semi-)automatic approach is desirable. This application is challenging because the underlying search space has rich semantics, is high-dimensional, and unstructured. Hence, a computationally brute-force approach would be unscalable and potentially infeasible. To address that problem, we develop a sophisticated approach of designing complex mutation operators. We define ‘patterns’ for constructing mutation operators and report a successful case study. Furthermore, the code of the evolved model transformation is required to have high maintainability and extensibility, that is, the code should be easily readable by domain experts. We report an evaluation of this approach in a software engineering case study. AU - Kühne, Thomas AU - Hamann, Heiko AU - Arifulina, Svetlana AU - Engels, Gregor ID - 169 T2 - Proceedings of the 19th European Conference on Genetic Programming (EuroGP 2016) TI - Patterns for Constructing Mutation Operators: Limiting the Search Space in a Software Engineering Application ER - TY - GEN AU - Handirk, Tobias ID - 1082 TI - Über die Rolle von Informationen in Verkehrsnetzwerken ER - TY - THES AU - Cord-Landwehr, Andreas ID - 154 SN - 978-3-942647-72-4 TI - Selfish Network Creation - On Variants of Network Creation Games VL - 353 ER - TY - CONF AB - Consider a scheduling problem in which a set of jobs with interjob communication, canonically represented by a weighted tree, needs to be scheduled on m parallel processors interconnected by a shared communication channel. In each time step, we may allow any processed job to use a certain capacity of the channel in order to satisfy (parts of) its communication demands to adjacent jobs processed in parallel. The goal is to find a schedule that minimizes the makespan and in which communication demands of all jobs are satisfied.We show that this problem is NP-hard in the strong sense even if the number of processors and the maximum degree of the underlying tree is constant.Consequently, we design and analyze simple approximation algorithms with asymptotic approximation ratio 2-2/m in case of paths and a ratio of 5/2 in case of arbitrary trees. AU - König, Jürgen AU - Mäcker, Alexander AU - Meyer auf der Heide, Friedhelm AU - Riechers, Sören ID - 157 T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA) TI - Scheduling with Interjob Communication on Parallel Processors ER - TY - JOUR AB - Abstract—Max-min fairness (MMF) is a widely known approachto a fair allocation of bandwidth to each of the usersin a network. This allocation can be computed by uniformlyraising the bandwidths of all users without violating capacityconstraints. We consider an extension of these allocations byraising the bandwidth with arbitrary and not necessarily uniformtime-depending velocities (allocation rates). These allocationsare used in a game-theoretic context for routing choices, whichwe formalize in progressive filling games (PFGs). We present avariety of results for equilibria in PFGs. We show that these gamespossess pure Nash and strong equilibria. While computation ingeneral is NP-hard, there are polynomial-time algorithms forprominent classes of Max-Min-Fair Games (MMFG), includingthe case when all users have the same source-destination pair.We characterize prices of anarchy and stability for pure Nashand strong equilibria in PFGs and MMFGs when players havedifferent or the same source-destination pairs. In addition, weshow that when a designer can adjust allocation rates, it is possibleto design games with optimal strong equilibria. Some initial resultson polynomial-time algorithms in this direction are also derived. AU - Harks, Tobias AU - Höfer, Martin AU - Schewior, Kevin AU - Skopalik, Alexander ID - 159 IS - 4 JF - IEEE/ACM Transactions on Networking TI - Routing Games With Progressive Filling ER - TY - CONF AB - In this paper we consider a strategic variant of the online facility location problem. Given is a graph in which each node serves two roles: it is a strategic client stating requests as well as a potential location for a facility. In each time step one client states a request which induces private costs equal to the distance to the closest facility. Before serving, the clients may collectively decide to open new facilities, sharing the corresponding price. Instead of optimizing the global costs, each client acts selfishly. The prices of new facilities vary between nodes and also change over time, but are always bounded by some fixed value α. Both the requests as well as the facility prices are given by an online sequence and are not known in advance.We characterize the optimal strategies of the clients and analyze their overall performance in comparison to a centralized offline solution. If all players optimize their own competitiveness, the global performance of the system is O(√α⋅α) times worse than the offline optimum. A restriction to a natural subclass of strategies improves this result to O(α). We also show that for fixed facility costs, we can find strategies such that this bound further improves to O(√α). AU - Drees, Maximilian AU - Feldkord, Björn AU - Skopalik, Alexander ID - 149 T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA) TI - Strategic Online Facility Location ER - TY - GEN ED - Dressler, Falko ED - Meyer auf der Heide, Friedhelm ID - 163 TI - Proceedings of the 17th ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc) ER - TY - CONF AB - Defining, measuring, and comparing the quality and efficiency of rendering algorithms in computer graphics is a demanding challenge: quality measures are often application specific and efficiency is strongly influenced by properties of the rendered scene and the used hardware. We survey the currently employed evaluation methods for AQ1 the development process of rendering algorithms. Then, we present our PADrend framework, which supports systematic and flexible development, evaluation, adaptation, and comparison of rendering algorithms, and provides a comfortable and easy-to-use platform for developers of rendering algorithms. The system includes a new evaluation method to improve the objectivity of experimental evaluations of rendering algorithms. AU - Fischer, Matthias AU - Jähn, Claudius AU - Meyer auf der Heide, Friedhelm AU - Petring, Ralf ED - Kliemann, Lasse ED - Sanders, Peter ID - 16351 T2 - Algorithm Engineering TI - Algorithm Engineering Aspects of Real-Time Rendering Algorithms VL - 9220 ER -